In an industrial X-ray CT system, generally, a rotary stage which rotates around an axis orthogonal to an X-ray optical axis is arranged between an X-ray source and an X-ray detector, which are disposed opposite each other. X-rays are irradiated onto a subject in a state the subject is held on the rotary stage. X-ray transmission data are obtained from the X-ray detector every time the rotary stage is rotated by a predetermined minute angle. A tomogram of the subject taken along a plane orthogonal to a rotational axis of the rotary stage is reconstructed by using the obtained X-ray transmission data (see, e.g., Patent Document 1). The rotary stage is usually movable in a direction of the X-ray optical axis (direction of the x-axis) and in directions orthogonal thereto (directions of the y-axis and the z-axis) by a moving mechanism. There is known an X-ray CT system provided with an xy table on the rotary stage, for moving the subject in two directions (directions of the x-axis and the y-axis) orthogonal to the rotational axis.
Patent Document 1: Japanese Patent Laid-Open Publication No. 2004-117024